Method of bending tubular members



July 3, '1962 w, NEELY 3,042,099

METHOD OF BENDING TUBULAR MEMBERS Filed April 23, 1959 l I INVENTOR.

WILLIHM H- NEELY Unite States Patent 3,042,099 METHOD OF BENDING TUBULAR MEMBERS William H. Neely, Cleveland, Ohio, assignor, by mesne assignments, to Hoover Ball & Bearing Co., Saline, Mlch., a corporation of Michigan Filed Apr. 23, 1959, Ser. No. 808,345 Claims. (Cl. 153-2) This invention relates in general to bending of elongated tubular members and has particular reference to an improved, simplified method of bending a tubular member without bulging.

At present, bending of tubular members is effected by filling these members with sand, gravel, resin, or chainlike structures of interconnected balls, mandrels, etc. However, this presently used procedure in bending operations prevents only collapsing of the tubular members, but permits their deforming, and generally necessitates re-shaping of thus bent portions of tubular members.

The primary object of this invention is to provide an improved and simplified method of bending a tubular member, the method including two successive steps, one step effecting indentation of two opposed wall portions of the tubular member and the other step effecting bending of two other opposed wall portions of the tubular member, which latter wall portions are angularly related to the first wall portions to promote by bending operations folding of the indented wall portions upon each other and avoid bulging of all wall portions of the tubular member.

Another object of the invention is to provide a method of bending a tubular member, the method including two successive steps, one step effecting symmetrical longitudinal indenting of two opposed wall portions of the tubular member in a plane through the longitudinal axis thereof and the other step effecting bending of two other opposed wall portions of the tubular member, which latter wall portions are related at a right angle to the first two opposed wall portions to promote by bending operations cooperative symmetrical folding of the indented wall portions upon each other and avoid bulging of all wall portions of the tubular member.

This method is well suited for bending tubular members of rectangular cross section into furniture and automobile seat frames. The use of rectangularly shaped tubular members substantially facilitates attachment of springs, spring structures and other elements, and provides sufficient tensile and torsional resistance for all load requirements.

A further object of the invention therefore is to provide a method of bending a tubular member of rectangular cross section, the method including two successive steps: (1) first effecting localized symmetrical longitudinal in- 3,042,099 Patented July 3, 1962 any desired shape and have many other advantages fully appreciated by those skilled in the art.

The accompanying drawing more or less diagrammatically illustrates the successive steps taken in bending a tubular member in accordance with the method of the invention.

In the drawing:

FIG. 1 is a diagrammatic cross-sectional view of an indenting die arrangement seating a tubular member of rectangular cross section prior to indentation of opposed wall portions thereof.

FIG. 2 is a view similar to FIG. 1, showing the tubular member indented.

FIG. 3 is a diagrammatic side view of a bending die arrangement supporting the indented tubular member.

FIG. 4 is a cross-sectional view at about the center of FIG. 3.

denting of two opposed walls of the tubular member, and y (2) next effecting localized bending of the other two op posed walls of the tubular member, and localized approach of the last two opposed walls toward each other both to cause localized bending of the said last two opposed walls at curvatures of relatively small radii and to cause localized folding of the said first two opposed walls upon each other, thereby to produce reenforced bends by a plurality of packed layers of material.

A still further object of the invention is to provide a method of bending a tubular member of rectangular cross section in the manner described above, in which the indented area of the two opposed wall portions is small to effect bending of the tubular member in a limited area and permit quick merging of the folded opposed wall portions into straight wall portions extended at right angles thereto.

As a result, tubular members bent in accordance with the method disclosed herein, shaped without bulging and undesired tensile or torsional stresses, are readily bent to FIG. 5 is a side view similar to FIG. 3, showing after bending operations have been terminated.

FIG. 6 is a side view of the bent tubular member; and

FIG. 7 is a cross-sectional view at the center of FIG. 6.

Referring now more particularly to the exemplified form of structure shown in the drawing and bent in accordance with the method disclosed herein, reference numeral 2 denotes a tubular member of rectangular cross section, which includes oppositely arranged top and bottom walls 3 and 4 and oppositely arranged side walls 5 and 6. Tubular member 2 is bent in successive method steps, step one effecting longitudinal indenting or crimping of side walls 5 and 6 and step two effecting bending of top and bottom walls 3 and 4 about a transverse axis through the side walls and their forcible approach toward each other. indenting of side walls 5 and 6 is accomplished in a die arrangement 7 which includes supports 8 seating the tubular member 2, and identically constructed oppositely arranged shiftable die members 9 and 10 slidably mounted on base 11 in axial alignment with respect to each other and at a right angle with respect to tubular member 2.

The die members 9 and include die heads .12 and 13, respectively, which have their opposed end portions slotted by cross slots 14 and 15, dimensioned to fit tubular member 2 and hold same against rotation in indenting operations. Die heads 12 and 13 have symmetrically arranged in their cross slots 14 and .15 elongated ridges 16 and 17 which cooperate in indenting walls 5 and 6 when die members 9 and 10 are shifted toward tubular member 2 and form elongated indentations 18 and 19 in said walls 5 and 6, which indentations extend parallel to each other and symmetrical to said side walls.

The thus indented tubular member 2 in the second step of the bending method of the invention is bent in a bending die arrangement 20 embodying two longitudinally spaced tiltable lever members 21, 22 which are tiltably supported on pivot pins 23, 24 in perforated ear portions 25, 26 of a base not shown. Bending die arrangement 20 includes a shiftable punch-like die member 27 arranged in upwardly spaced relation with respect to lever members 21, 22 of identical construction which each include a flat supporting top 28, 29 and side flanges 30, .31, respectively, arranged to locate and guide tubular member 2 on fiat supporting tops 28, 29' of tiltable lever members 21, 22. The previously indented tubular member 2 seated on supporting tops 28 and 29 of bending die arrangement 20 is bent by downward shifting of punch-like die member 27 which engages with its reduced head portion 32 top wall 3 of the tubular member and forces said top wall toward bottom wall 4, thus collapsing the tube in the bending zone. The pivotal tilting of the lever members 21, 22 serves to semi-floatingly resist bending of the tubular member during its final forming.

The described bending operations assure smooth curving of bottom wall 4, produce a U-shaped bend in top Wall 3 and fold side Walls 5 and 6 upon each other to provide tubular member 2 with a reenforced sharp bend 33, the apex 34 of which embodies superposed layers of wall portions. Indenting of side walls 5 and 6 reduces the height of the tubular member and eliminates possible bulging of wall portions beyond the confines of the tubular member 2 before its deforming and bending.

Although pivot pins 23, 24 are shown parallel, and lever members 2 1, 22 are shown coplanar, I contemplate any desired angular orientation of one pivot pin and lever member relative to the other so as to bend one arm of the tubular member into any desired plane and angular orientation relative to the other.

Though but a single example of carrying out the method of bending tubular members has been disclosed herein, it is obvious that many and varied types and forms of bent tubular elements may be produced by the bending method of the invention, all within the spirit and scope of the appended claims.

Having thus described my invention what I claim is:

1. In a method of bending a tubular member, the improvement which comprises inwardly longitudinally crimping opposite sides of said member in the bending zone, and thereafter bending said member in said zone about a transverse axis through said opposite sides.

2. In a method of bending a tubular member, the improvement which comprises inwardly longitudinally crimping opposite sides of said member in the bending Zone, and thereafter folding the crimped sides on themselves, and bending said member in said zone about a transverse axis through said opposite sides.

3. The method defined in claim 2 wherein said folding and said bending are concurrent.

4. In a method of bending a rectangular tube, the improvement which comprises inwardly longitudinally crimping opposite sides of said tube in the bending zone, and thereafter collapsing said tube in said zone with the crimped sides folded on themselves, and bending said tube in said zone about an axis substantially parallel to said crimped sides.

5. The method defined in claim 4 wherein said collapsing and said bending are effected by exerting pressure on one of the remaining tube sides in the bending zone, while yieldingly supporting tube portions on opposite sides of the bending zone.

References Cited in the file of this patent UNITED STATES PATENTS out 

